1. Field of the Invention
The present invention is in the field of medical electronics and specifically relates to apparatus and method for the detection, definition and classification of ectopic heartbeats using two-channel vector ECG signals.
2. The Prior Art
It has long been known that medically-significant vector electrocardiograms can be produced through the use of a three-lead system. Previous studies have already indicated merit in the vector cardiographic analysis of anomalous and ectopic beats for identifying the site of origin of ectopic beats. Such anomalous beats not only commonly result in alteration of readily apparent direction and magnitude of QRS and T force vectors, but also affect the direction of rotation QRS vector forces, often accompanied by abnormal delays of QRS vector inscription. The latter characteristics are not readily apparent in analog electrocardiographic signals, and thus the vectorcardiogram gives additional discriminative data. The adjunctive vectorcardiographic data complements the analog cardiographic signal data by providing a visual integrated picture of the electrical activity.
The preponderance of the diagnostic vector electrocardiographic studies have been carried out using the Frank lead system or a modified McFee lead system, which lead systems were designed to measure horizontal, longitudinal and saggital plane forces.
In U.S. Pat. application Ser. No. 786,252, filed Apr. 11, 1977 for VECTORCARDIOGRAPHIC METHOD FOR AMBULATORY PATIENTS, Dr. Harold L. Kennedy discloses a method for obtaining vectorcardiographs using a two-lead system. This simplified lead system using the V.sub.1 and V.sub.5 electrode sites was developed specifically to facilitate diagnosis and identification of cardiac dysrhythmias, particularly anomalous extrasystols, as seen in the lead V.sub.1, and to best detect left ventricular myocardial ischemia by employing a commonly used exercise-sensitive lead, chest bipolar lead V.sub.5.
The simplified two-lead system disclosed in the Kennedy application identified above has proven to be medically useful for producing vectorcardiograms for the diagnosis of arrhythmias, and consequently, with the widening use of the method, increasing amounts of two-channel vectorcardiographic signals can be expected to be produced. Increasing amounts of time and manpower will be devoted to the analysis of such data, and the need for apparatus for automatically analyzing the data has become clear.